Video Display System, Video Display Device, Its Control Method, and Information Storage Medium

1. A video display system having a first video display device and a second video display device, connected to each other for communication, wherein the first video display device comprises: a first video and sound output unit configured to display first video data and reproduce first sound data; an operation input unit configured to receive an operation input of a user; and a data sending unit configured to send second video data in accordance with the first video data and second sound data in accordance with the first sound data to the second video display device; an encoding unit configured to encode the first video data and the first sound data into a data format, which the second video display device is able to handle, to produce second video data and second sound data; a first receiving unit configured to receive group identification information from each of a plurality of second video display devices, the identification information identifying, among a plurality of groups, a group to which each of the plurality of second video display devices belongs, wherein the plurality of second video display devices are connected to the first video display device for communication; and a related information generation unit configured to generate related information for relating each of the plurality of second video display devices to any of the plurality of groups, in response to the received group identification information, wherein the encoding unit produces the plurality of pieces of the second video data and the plurality of pieces of the second sound data, which are mutually different, in response to the plurality of groups, and wherein the data sending unit sends the plurality of pieces of the second video data and the plurality of pieces of the second sound data, which are produced for the plurality of groups respectively, to the second video display device that is related to the group in the related information, wherein the second video display device comprises: a data receiving unit configured to receive the second video data and the second sound data; a second video and sound output unit configured to display the second video data and reproduce the second sound data; and an operation information sending unit configured to receive the operation input of the user and send operation information indicating content of the operation input to the first video display device, wherein the first video display device operates in accordance with the operation input received by the operation input unit in a first operation mode in which the first video and sound output unit displays the first video data and reproduces the first sound data, wherein the first video display device operates in accordance with the operation information sent by the operation information sending unit of the second video display device as the operation input received by the operation input unit in a second operation mode in which the data sending unit sends the second video data and the second sound data to the second video display device, and wherein the first video and sound output unit changes the first video data and the first sound data using the operation information sent by the operation information sending unit of the second video display device in a received display mode and the content of the first video data and the first sound data has interactive nature.

2. A first video display device connected for communication to a second video display device, comprising: a first video and sound output unit configured to display first video data and reproduce first sound data; an operation input unit configured to receive an operation input of a user; a data sending unit configured to send second video data in accordance with the first video data and second sound data in accordance with the first sound data to the second video display device; an operation information receiving unit configured to receive operation information that is sent by the second video display device upon receiving the operation input of the user, the operation information indicating content of the operation input; an encoding unit configured to encode the first video data and the first sound data into a data format, which the second video display device is able to handle, to produce the second video data and the second sound data; a first receiving unit configured to receive group identification information from each of a plurality of second video display devices, the identification information identifying, among a plurality of groups, a group to which each of the plurality of second video display devices belongs, wherein the plurality of second video display devices are connected to the first video display device for communication; and a related information generation unit configured to generate related information for relating each of the plurality of second video display devices to any of the plurality of groups, in response to the received group identification information, wherein the first video display device operates in accordance with the operation input received by the operation input unit in a first operation mode in which the video and sound output unit displays the first video data and reproduces the first sound data, wherein the first video display device operates in accordance with the operation information sent by the second video display device as the operation input received by the operation input unit in a second operation mode in which the data sending unit sends the second video data and the second sound data to the second video display device, wherein the first video and sound output unit changes the first video data and the first sound data using the operation information sent by the operation information sending unit of the second video display device in a received display mode and the content of the first video data and the first sound data has interactive nature, wherein the encoding unit produces the plurality of pieces of the second video data and the plurality of pieces of the second sound data, which are mutually different, in response to the plurality of groups, and wherein the data sending unit sends the plurality of pieces of the second video data and the plurality of pieces of the second sound data, which are produced for the plurality of groups respectively, to the second video display device that is related to the group in the related information.

3. The first video display device according to claim 2 , further comprising a unit configured to respectively receive identification information from a plurality of second video display devices, which are connected to the first video display device for communication, wherein the encoding unit produces a plurality of portions of the second video data and a plurality of portions of the second sound data, which are mutually different, and wherein data sending unit sends the plurality of portions of the second video data and the plurality of portions of the second sound data, which are mutually different, to each of the plurality of second video display devices that are specified by the identification information.

4. The first video display device according to claim 2 , further comprising: a second receiving unit configured to receive, from the plurality of second video display devices, change information for instructing a change of the groups to which the second video display devices belongs respectively; and an updating unit configured to update the related information generated by the related information generation unit, based on the received change information, wherein the data sending unit changes, in response to the updated related information, the second video data and the second sound data to be sent to the second video display device that has sent the change information.

5. The video display system according to claim 1 , wherein the data format of the second video data is different from the data format of the first video data.

6. The video display system according to claim 1 , wherein the data format of the second sound data is different from the data format of the first sound data.

7. The first video display device according to claim 2 , wherein the data format of the second video data is different from the data format of the first video data.

8. The first video display device according to claim 2 , wherein the data format of the second sound data is different from the data format of the first sound data.

9. The video display system according to claim 1 , wherein the first video and sound output unit changes, in response to the operation information sent by the operation information sending unit of the second video display device, content of the first video data and the first sound data in the second operation mode in which the data sending unit sends the second video data to the second video display device.

10. The first video display device according to claim 2 , wherein the first video and sound output unit changes, in response to the operation information sent by the operation information sending unit of the second video display device, content of the first video data and the first sound data in the second operation mode in which the data sending unit sends the second video data to the second video display device.

11. A video display method for a video display system having a first video display device and a second video display device, connected to each other for communication, comprising: displaying first video data and reproducing first sound data by a first video and sound output unit; receiving an operation input of a user by an operation input unit; sending second video data in accordance with the first video data and second sound data in accordance with the first sound data to the second video display device by a data sending unit; receiving the second video data and the second sound data by a data receiving unit; displaying the second video data and reproducing the second sound data by a second video and sound output unit; and receiving the operation input of the user and sending operation information indicating content of the operation input to the first video display device by an operation information sending unit; encoding the first video data and the first sound data into a data format, which the second video display device is able to handle, to produce the second video data and the second sound data; receiving group identification information from each of a plurality of second video display devices, the identification information identifying, among a plurality of groups, a group to which each of the plurality of second video display devices belongs, wherein the plurality of second video display devices are connected to the first video display device for communication; and generating related information for relating each of the plurality of second video display devices to any of the plurality of groups, in response to the received group identification information, wherein the first video display device includes the first video and sound output unit, the operation input unit, and the data sending unit, wherein the second video display device includes the data the receiving unit, the second video and sound output unit, and the operation information sending unit, wherein the first video display device operates in accordance with the operation input received by the operation input unit in a first operation mode in which the first video and sound output unit displays the first video data and reproduces the first sound data, wherein the first video display device operates in accordance with the operation information sent by the operation information sending unit of the second video display device as the operation input received by the operation input unit in a second operation mode in which the data sending unit sends the second video data and the second sound data to the second video display device, wherein the first video and sound output unit changes the first video data and the first sound data using the operation information sent by the operation information sending unit of the second video display device in a received display mode and the content of the first video data and the first sound data has interactive nature, wherein the encoding step produces the plurality of pieces of the second video data and the plurality of pieces of the second sound data, which are mutually different, in response to the plurality of groups, and wherein sending second video data step includes sending the plurality of pieces of the second video data and the plurality of pieces of the second sound data, which are produced for the plurality of groups respectively, to the second video display device that is related to the group in the related information.

12. A video display method for a first video display device connected for communication to a second video display device, comprising: displaying first video data and reproduce first sound data by a first video and sound output unit; receiving an operation input of a user by an operation input unit; sending second video data in accordance with the first video data and second sound data in accordance with the first sound data to the second video display device by a data sending unit; and receiving operation information that is sent by the second video display device upon receiving the operation input of the user and indicates content of the operation input by an operation information receiving unit, encoding the first video data and the first sound data into a data format, which the second video display device is able to handle, to produce the second video data and the second sound data; receiving group identification information from each of a plurality of second video display devices, the identification information identifying, among a plurality of groups, a group to which each of the plurality of second video display devices belongs, wherein the plurality of second video display devices are connected to the first video display device for communication; and generating related information for relating each of the plurality of second video display devices to any of the plurality of groups, in response to the received group identification information, wherein the first video display device operates in accordance with the operation input received by the operation input unit in a first operation mode in which the first video and sound output unit displays the first video data and reproduces the first sound data, wherein the first video display device operates in accordance with the operation information sent by the operation information sending unit of the second video display device as the operation input received by the operation input unit in a second operation mode in which the data sending unit sends the second video data and the second sound data to the second video display device, wherein the first video and sound output unit changes the first video data and the first sound data using the operation information sent by the operation information sending unit of the second video display device in a received display mode and the content of the first video data and the first sound data has interactive nature, wherein the encoding step produces the plurality of pieces of the second video data and the plurality of pieces of the second sound data, which are mutually different, in response to the plurality of groups, and wherein sending second video data step includes sending the plurality of pieces of the second video data and the plurality of pieces of the second sound data, which are produced for the plurality of groups respectively, to the second video display device that is related to the group in the related information.

13. A non-transitory computer readable medium storing a program for a first video display device connected for communication to a second video display device, the program for causing a computer to function as: a first video and sound output unit configured to display first video data and reproduce first sound data; an operation input unit configured to receive an operation input of a user; a data sending unit configured to send second video data in accordance with the first video data and second sound data in accordance with the first sound data to the second video display device; an operation information receiving unit configured to receive operation information that is sent by the second video display device upon receiving the operation input of the user and indicates content of the operation input, an encoding unit configured to encode the first video data and the first sound data into a data format, which the second video display device is able to handle, to produce the second video data and the second sound data; a first receiving unit configured to receive group identification information from each of a plurality of second video display devices the identification information identifying, among a plurality of groups, a group to which each of the plurality of second video display devices belongs, wherein the plurality of second video display devices are connected to the first video display device for communication; and a related information generation unit configured to generate related information for relating each of the plurality of second video display devices to any of the plurality of groups, in response to the received group identification information, wherein the first video display device operates in accordance with the operation input received by the operation input unit in a first operation mode in which the first video and sound output unit displays the first video data and reproduces the first sound data, wherein the first video display device operates in accordance with the operation information sent by the operation information sending unit of the second video display device as the operation input received by the operation input unit in a second operation mode in which the data sending unit sends the second video data and the second sound data to the second video display device, wherein the first video and sound output unit changes the first video data and the first sound data using the operation information sent by the operation information sending unit of the second video display device in a received display mode and the content of the first video data and the first sound data has interactive nature, wherein the encoding unit produces the plurality of pieces of the second video data and the plurality of pieces of the second sound data, which are mutually different, in response to the plurality of groups, and wherein the data sending unit sends the plurality of pieces of the second video data and the plurality of pieces of the second sound data, which are produced for the plurality of groups respectively, to the second video display device that is related to the group in the related information.